Loud speaker



1934 R. VERMEULEN Er AL 1,947,749

LOUD SPEAKER Filed March 5, 1929 RQELOF VERMEULEN AREND 'HMS VAN URK Patented Feb. 20, 1934 LOUD SPEAKEB Roelof Vermeulen, Arend Thomas Van Urk, and

Cornelis Loman, Eindhoven,

Netherlands. al

signors to Radio Corporation of Amerlca, a corporatlon of Delaware Applioatlon March 5, 1929, Serial No.

and in the Netherlands April 27, 1928 4 Claims. (01.173-109) The invention relates to loudspeakers which are provided with a plurality of magnet systems. Usually, loudspeakers of this type are provided with as many vibrating members as there are magnet systems and the vlbrating mem bers are preferably so arranged that their axes are parallel to each other, each of the said vibrating members being actuated by one of the magnet systems.

Aceordng to the present invention, the loudspeaker comprises a vibrating member constituted by a diaphragm of large surface, whlch is provided with a plurality of protuberances whieh are coupled either separately or in groups with one of the magnet systems.

In operation the protuberance or protuberances substantiallly reproduce the high irequencies whereas the diaphragm reproduces principally the low irequencies. In order to facilitatethis, the protuberances.may be made, tor example. oi' thin paper and the diaphragm of thick paper or, if desired, the protuberances and the diaphragm may be made of different materials.

According to en approved embodiment of the invention, a fiat dlaphragm is provided with conical protuberances each of which is connected with a separate magnet system. The edge of the diaphragm is rigidly clamped in a frame and the diaphragm is provided with circular i'olds which form a yielding support therefor.

Instead of a conical shape the protuberances may also be given any other shape. It is also possible to use instead of a flat diaphragm a spherical or conical diaphragm. Driving units of the electrodynamic or electrostatic types may also be used in place of the magnetic system shown.

The invention will be more clearly understood by reterring to the accompanying drawing in whioh:

Figure 1 is a plan view of a vibrating member according to the inventiony Flgure 2 is a cross section taken en the line II--II of Figure 1;

Flgure 3 is. a front view of the loudspeaker according to the invention.

In the approved embodiment iilustrated by the drawing a flat circular diaphragm 1 is provided with flve protuberances 2 which are conical in shape. Each of these protuberances laconnected wlth a separate maanet system 3 but if it is desired, a group of the protuberances may be coupied to a single magnet system. The diaphragm 1 is rigidly clamped in a frame 5 and lt is provided with circular i'olds 4 in order to enable it to move in a dlrection parallel to its axis.

Various other types of clamping and supporting means may be used, however, without departing trom the spirit 01' the inventlon.

It is to be understood that; the novel features 01' the invention may be embodied in various ether arrangements and that accordingly we do not wish to be restricted to the structure 01' the approved iorm of our invention as illustrated by the accompanying drawlng.

We claim:

1. A sound reproducer comprising a plurality oi' magnet systems, a large diaphragm o1' thick paper, a plurality of protuberances on said diaphragm, eaoh o1' said-protuberances being oi' thin paper, and a connection trom each of said protuberances to a different one of said plurality of magnet systerns.

2. In a loud speaker having a plurality of actuating units. a dlaphragm comprising a plane member, a plurality of acoustically similar conical diaphragms rigldly mounted thereon at spaced intervals, said conical diaphragms being mounted at their large end, and means at the small end of each conical diaphragm tor attachment to a driving unit.

3. The structure of claim 2 in whlch the plane member is made of paper and the conical diaphragms are separate members rigidly united thereto.

4. The structure of claim 2 in whioh the plane diaphragm has a peripheral portion having corrugations formed thereln and adapted to be clamped along its outer endge.

ROELOF VERMEULEN. AREND THOMAS VAN URK. CORNELIS LOMAN. 

